The invention relates to a method fixing an expansion anchor to a substrate.
An expansion anchor is, for example, known from EP 2886881 A1. The expansion anchor is used to anchor mounting parts to a hole in a solid substrate, for example a concrete substrate. The known expansion anchor has an elongated bolt, which is provided with an expansion cone in the area of its front end, and which has a thread in the area of its rear end, on which a nut is seated. The expansion cone expands toward the front end, i.e., against the pull-out direction. In the pull-out direction, an expansion sleeve is situated on the bolt offset to the expansion cone. Toward the front end of the bolt on the expansion cone, this expansion sleeve is displaceably mounted on the bolt. The bolt has an annular collar configured as one piece with the bolt which forms an axial stop which delimits the displacement of the expansion sleeve relative to the bolt towards the rear end of the bolt.
When setting the anchor, the first end of the bolt is pounded into the hole in the substrate against the pull-out direction. The expansion sleeve is entrained by the annular collar and therefore also reaches the hole. The nut is then screwed on until it abuts on the substrate or a mounting part, which may be present as an abutment, and it is then tightened further until a predefined torque is reached. This tightening of the nut causes the bolt to be pulled back out of the hole to a certain extent in the pull-out direction. After the expansion anchor is pounded in, the expansion sleeve is caught on the inner hole wall and is therefore retained upon withdrawal of the bolt in the hole. As a result, the expansion cone of the bolt is drawn into the expansion sleeve, the expansion sleeve being expanded due to the increasing diameter of the expansion cone. The expansion anchor is jammed with the expansion sleeve in the substrate, so that tensile loads may be transferred into the substrate. This basic principle may preferably also be used in the method according to the present invention.
DE 10204591 A1 teaches a method for setting an expansion anchor in which mortar is additionally filled into the hole after the expansion anchor has been anchored in the hole. The cured mortar is supposed to support the expansion anchor in the radial direction in the hole. DE 10204591 A1 provides a seal which prevents mortar entering a front region of the expansion anchor and the hole, and the seal can also be a circumferential bead on the anchor bolt. According to DE 10204591 A1, a small amount of mortar passing the seal in the front region of the hole can be tolerated under certain circumstances. In order to allow subsequent expansion of the expansion anchor in the case of expansion of the hole, for example as a result of crack formation in the substrate, a mortar can be selected, according to DE 10204591 A1, which does not fixedly adhere to the expansion anchor and/or the hole.
DE 10360156 A1 discloses an expansion anchor in which depressions are formed in the shell surface of the bolt which allow a mortar mass, which can be introduced into the hole, to penetrate. These depressions may be conically shaped.
Further anchors, in which expansion elements are used in combination with curable masses, are known from the publications DE102006000475 A1, DE10216897 A1, DE10060510 A1, WO9857035 A1, U.S. Pat. No. 5,919,006A, U.S. Pat. No. 5,636,945A, U.S. Pat. No. 5,042,961 A U.S. Pat. No. 5,064,312 A, U.S. Pat. No. 4,601,614 A, U.S. Pat. No. 4,516,883A, U.S. Pat. No. 4,556,344 A, U.S. Pat. No. 3,702,060A, U.S. Pat. No. 3,695,045A, U.S. Pat. No. 3,204,416A, U.S. Pat. No. 3,326,004A, U.S. Pat. No. 2,952,129 A, U.S. Pat. No. 3,379,019 A and U.S. Pat. No. 2,667,037 A.
DE102011055878 A1 describes a method for anchoring an expandable anchor in which the expansion sleeve is adhered in an anchor shaft, whereas the anchor bolt is not adhered to anchor hole.
An injection washer emerges from WO 11116918 A2 which has a central hole, a filling opening and a ventilation opening. This injection washer is used in a method for subsequent strengthen of a fastening means to be inserted into a hole which is already located in its mounted state, for example a heavy-duty anchor with an expandable sleeve. A further washer with a through hole for filling the mortar mass into the hole is known from DE10111470 A1.
DE 19818739 A1 describes a retrospective reinforcement connection, a reinforced bar being provided in the lower region with at least one conical sleeve and is provided in the upper region with a plastic sleeve and the annular gap is filled with curable mass.
EP 0251887 B1 describes an anchor to be cast, in which the bolt is surrounded between its thread section and its front end by a tube made of deformable material which has a lower mechanical strength than that of the once-cured potting resin.
DE 2745438 A1 describes an anchor which has an expanding expansion part which exerts an expansion force on surrounding cured binder segments. DE 19712425 A1 deals with a compound anchor which consists of an anchor rod which has at least one cone section expanded in the insertion direction and can be anchored by means of a compound mass in a hole of a substrate.
The object of the invention is to indicate a method for fixing an expansion anchor which opens up a particularly wide application spectrum for the expansion anchor with particularly little effort and easy implementability and in particular allows particularly good load values.
In accordance with method according to the invention for fixing an expansion anchor on a substrate:
an expansion anchor, which has at least one expansion sleeve and at least one bolt passing through the expansion sleeve, is provided, the bolt having a load application zone for introducing a tensile force into the bolt, a middle zone axially adjacent to the load application zone and an anchoring zone axially adjacent to the middle zone, the expansion sleeve being arranged at the height of the anchoring zone, the bolt having an expansion cone in the anchoring zone which pushes the expansion sleeve radially outwards to anchor the expansion anchor when the expansion cone is moved relative to the expansion sleeve in a pull-out direction and the bolt having an annular collar configured as one piece with the bolt between the middle zone and the anchoring zone, at which the bolt is formed larger in cross-section than in the adjacent middle zone and which forms an axial stop for the expansion sleeve,
the anchoring zone and at least one part of the middle zone of the bolt together with the expansion sleeve are inserted into a hole in the substrate against the pull-out direction,
the bolt is then moved with the expansion cone relative to the expansion sleeve in the pull-out direction whereby the expansion anchor is anchored to the wall of the hole,
the space between the wall of the hole and the bolt is then filled with a curable mass to the height of at least one part of the middle zone such that the curable mass reaches, at the middle zone, up to the annular collar of the bolt and
the curable mass located in the space between the wall of the hole and the bolt is cured.
A basic concept of the invention is considered providing a collar configured as one piece with the bolt and protruding radially with respect to the rear middle zone on an expansion anchor of the bolt type axially just before the anchoring zone and filling the annular space around the bolt of the expansion anchor with curable mass following the mechanical anchoring of the expansion anchor such that the collar abuts on the cured mass on its rear side at least in sections, preferably completely, after the curable mass has cured. In experiments, it has been surprisingly shown that such an approach can improve not only the dynamic transverse loadability of the expansion anchor, but surprisingly also the axial pull-out load.
An improvement of the pull-out loads could in particular be observed with such expansion anchors which are anchored in a hole which runs through a crack alternately opening and closing. After repeated crack opening cycles, notably increased residual pull-out forces could be observed here. These notably increased residual pull-out forces were associated with notably reduced anchor displacements and notably deeper concrete failure cones after repeated crack opening cycles. It is expected at present that the improved values should be traced back to a type of additional, positive-locking axial anchoring which results between the collar and the mass abutting on the collar and connected to the hole wall. Since the collar is arranged directly adjacent to the anchoring zone according to the invention, it also forms the axial sleeve stop, the load introduction using this mechanism can take place particularly deep in the hole and thus be carried out effectively. Since the collar is configured as one piece with the bolt, particularly high tensile forces can be transferred to the bolt in a particularly reliable manner.
The filling of the space between the wall of the hole and the bolt can, on the one hand, provide the advantage in the configuration according to the invention that the complete anchor system is notably more rigid whereby higher loads can be achieved in the transverse-pull. In addition, notably higher pull-out values and lower displacement values of the anchor can also be achieved under seismic and dynamic conditions with the particular method process according to the invention, in which an additional positive-locking anchoring is formed on the collar similar to an indentation. As a result of the anchor initially expanding according to the invention and only then being filled, the anchor generally does not act like a classic compound anchor, but rather more like a mechanically anchored anchor with the additional advantages of an increased system rigidity and an additional indentation-like anchoring.
The middle zone of the bolt is located axially between the load application zone of the bolt and the anchoring zone of the bolt. The middle zone, the load application zone and the anchoring zone are in particular axially moved towards one another. Insofar as “radial”, “axial” and “circumferential direction” are mentioned in this description, this may in particular relate to the longitudinal axis of the bolt, which can, in particular, be the symmetry and/or middle axis of the bolt. A longitudinal section and/or a cross-section can also relate to this longitudinal axis. Insofar as mention is made here to the fact that an element is located “at the height” of another element, this may also in particular relate to this longitudinal axis, i.e., the height is measured at the longitudinal axis.
In the case of the step, according to the invention, of introducing the anchoring zone and at least one part of the middle zone of the bolt together with the expansion sleeve against the pull-out direction into a hole in the substrate, the entire middle zone and/or at least one part of the load application zone can also be introduced into the hole. The expansion sleeve is arranged, according to the invention, on the bolt, in particular fastened to the bolt, so as to be displaceable along the bolt.
The expansion anchor can, in particular, be a force-controlled expanding expansion anchor. The expansion sleeve and/or the bolt suitably consist of a metal material which can, for example, also be coated to specifically influence the friction. The substrate may in particular be a mineral construction material, preferably concrete. The curable mass can, for example, be a mortar or a synthetic resin. Depending on the composition of the mass, the curing of the mass can, for example, occur simply with the passage of time. Alternatively, curing by way of a supply of energy, in particular heat supply can for example be provided.
The expansion cone is preferably drawn into the expansion sleeve, when anchoring the expansion anchor, by way of a common axial movement of the bolt together with its expansion cone relative to the expansion sleeve. The expansion cone is suitably arranged, at least in the axial direction, fixed on the bolt. The expansion cone is preferably configured as one piece with the bolt. The expansion anchor according to the invention can preferably also be designated as an anchor of the bolt type.
The expansion sleeve is expediently pushed radially outwards from an inclined surface of the expansion cone and is pressed against the hole wall in the substrate when the expansion cone is moved axially relative to the expansion sleeve in the pull-out direction of the bolt. The expansion anchor is hereby anchored in the hole. The pull-out direction preferably runs parallel to the longitudinal axis of the bolt and/or shows from the hole in the substrate. The distance of the surface of the expansion cone from the longitudinal axis of the bolt expediently increases against the pull-out direction, i.e., with increasing distance from the load application zone. The surface of the expansion cone can be strictly conical. However, in accordance with the technical definition of an expansion cone, it does not have to be. For example, the surface of the expansion cone can also be convex or concave in the longitudinal section.
The curable mass is, according to the invention, only anchored after the mechanical anchoring, i.e., introduced into the space between bolt and wall after the expansion cone is drawn into the expansion sleeve and the expansion sleeve expands radially in order to prevent any undesired interaction of the curable mass with the mechanical anchoring mechanism. Following the curing of the curable mass, subsequent expansion of the sleeve can, however, be provided by the expansion cone and thus subsequent anchoring.
The collar forms a rear axial stop for the expansion sleeve which delimits a displacement of the expansion sleeve away from the expansion cone, i.e., a displacement of the expansion sleeve in the pull-out direction. The collar preferably has an annular or at least unbroken annular stop surface for the expansion sleeve, and the stop surface can run preferably perpendicular to the longitudinal axis of the bolt. The collar preferably forms an at least local cross-section maximum on the bolt, the axial stop on which the expansion sleeve strikes, is formed on the front side of the collar. The collar can also essentially comprise radial recesses. Preferably however, it comprises the form of a closed ring.
It is particularly preferred for a retaining ring made of curable mass to be formed between the wall of the hole and the bolt when filling the space, the mass abuts on the collar at the side of the collar facing the middle zone and which surrounds the bolt and it is also particularly preferred for the retaining ring to be cured. According to this embodiment, the entire collar abuts on the cured mass such that the hold values and the reliability can increase even further.
At least one part of the anchoring zone is also left free of curable mass. The space between the wall of the hole and the bolt is accordingly filled only partially with curable mass. Undesired interactions between the curable mass and the expansion mechanism are hereby avoided and the reliability can be increased even further. For example, the collar integrated on the bolt can form a seal which impedes a flow of the curable mass towards the anchoring zone.
It is also expedient for a curable mass to be used which adheres more strongly to the wall of the hole than to the bolt after curing. A curable mass can, in particular, be used which adheres to the wall of the hole, not, however, to the bolt after curing. According to this configuration, the cured curable mass, on the one hand, can serve as a positive-locking anchor for the collar on the substrate, on the other hand, the remaining bolt can be moved axially in the cured mass such that the mechanical expansion mechanism continues to remain operative. The reliability can be hereby increased even further. The cured mass can, in particular, have a fixed connection to the wall of the hole, however, can come loose from the bolt in the case of a crack opening.
The bolt can be designed thread-free in the middle zone, in particular substantially cylindrically. The above-described positive-locking anchor effect can be concentrated even better on the collar which may be advantageous in terms of the load values. For this reason, the bolt can, additionally or alternatively, be designed on the annular collar larger in cross-section than in the load application zone.
The bolt can have an outer thread in the load application zone. Alternatively or additionally the bolt can, however, also have an inner thread and/or a head.
A further preferred configuration of the invention is that an injection washer is provided which annularly surrounds the bolt and which has at least one channel and in that the space between the wall of the hole and the bolt is filled with curable mass through the channel of the injection washer. A particularly simple and also reliable filling is hereby achieved. The injection washer can, for example, be designed as described in DE 10111470 A1. The space between the wall of the hole and the bolt is expediently filled from the rear side of the bolt, i.e., from its load application zone and/or thread side, preferably by means of an injection washer.
The invention also relates to a fastening arrangement consisting of an expansion anchor and a substrate, the expansion anchor being fixed to the substrate by means of a method according to the invention. Features, which are explained in connection with the method according to the invention, can also be used with the fastening arrangement according to the invention, and vice versa, features, which are explained in connection with the fastening arrangement, can also be used with the method according to the invention.
The invention is explained in further detail below based on preferred exemplary embodiments, which are schematically represented in the enclosed Figures, and individual features of the exemplary embodiments shown below can essentially be implemented in the context of the invention individually or in combination.